(310f) Photobacteria-Based Biohydrogen Production from Organic Waste By the Use of Near-IR Light and Plasmonic Nanoparticles

An emerging hydrogen economy is amplifying a demand for clean hydrogen production technologies to better match the diverse applications of hydrogen. While conventional hydrogen applications are supplied by large central-station gas reforming units, emerging applications create a more disparate demand for hydrogen and thus require an innovative solution to the infrastructure and distribution hurdles that large central-station hydrogen production is facing. Our approach involves converting organic wastes to hydrogen gas. The simultaneous elimination of organic wastes and production of clean fuels will have an immense impact to both society and industrial manufacturing sector. Enhanced understanding of the interface between nanoparticles and photo-responsive bacteria (Rhodopseudomonas palustris) will further advance knowledge in interactions with biological systems. Although literature shows the production of gases by photobacteria but here we demonstrate the integration of photonics, biology, and nanostructured plasmonic materials for hydrogen production with lower greenhouse CO2 gas content at quantified light energy intensity and wavelength. Phototrophic purple non-sulfur bacteria are able to generate hydrogen as a byproduct of nitrogen fixation using energy absorbed from visible and near-IR (NIR) light. This type of biological hydrogen production has suffered from a low efficiency of converting light energy into hydrogen, in part due to light sources that do not exploit the organisms’ capacity for NIR absorption. We used NIR light sources and optically resonant gold-silica core-shell nanoparticles to increase light utilization of the bacteria to convert waste organic acids, such as acetic and maleic acids, to hydrogen. Further, management of the microbes leads to lower CO2 emissions while maximizing hydrogen production. Batch growth studies with Rhodopseudomonas palustris demonstrated > 2.5 fold increases in hydrogen production when grown under a NIR source (167±18 micromol H2) compared to a broad-band light source (60 ±6 μmol H2) at equal light intensity (130 W/m¬2). The addition of optically resonant gold-silica core-shell nanoparticles enhanced near field light utilization and further improved hydrogen production more than two-fold. The presentation will include hydrogen production rates, role of light intensity, use of filtered solar light, and optimization of bioreactor conditions to maximize hydrogen production with lower CO2 content. This work has been funded by the National Science Foundation, NIEHS, and by Southern Company.